Re: Vcc buss rails being pulled down.

Short of breaking out a milliohm meter, when I worked for a printer manufacturer and we had boards that had hidden shorts, we would use a sheet of temperature sensitive liquid crystal ( I think you can get sets of these from Edmund scientific still). Set the board on the bench, lay the sheet of liquid crystal over it, and connect the board to a variable dc supply. Slowly bring the voltage up. And the heat near the problem area will make the sheet change color. Was a pretty ingenious method my boss taught me.

On Oct 16, 2011, at 4:38 PM, litterbox99@mchsi.com wrote:

> I'm working on a Slot machine MPU, with
> similar 74xxx components like our arcade
> games.
>
> The Vcc buss is being pulled down to about 50mv.
> The LM340T5 runs very warm, so were keeping the
> power on time very low.
>
>
> Besides removing the IC's one at a time (and
> of course their not socketed ) is there a way
> to ID which component is at fault ?
>
> We've removed the IC's that are socketed, and
> checked for warm or hot components.
>
>
> Todd
>
>
>
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Received on Sun Oct 16 18:18:25 2011